Evaluation of interface toughness of bi-material Ni/Al by molecular dynamics method

Abstract

Bi-materials in submicron scale have been widely used in many industries, especially in the microelectronics industry. Due to the different deformation between the two material layers, damage usually occurs on the surface between the two material layers. In this paper, the Molecular dynamics (MD) method is used to investigate the mechanical properties of bi-material Ni/Al under the tensile strain. The examined Ni/Al structure has dimensions of 10.90 nm x 5.27 nm x 4.22 nm/10.93 nm x 5.26 nm x 4.21 nm, with strain rates of 1.83x108s-1, 5.48x108s-1, 1.83x109s-1 and 5.48x109s-1, respectively. The interactions between the atoms in the system are described by the EAM (Embedded Atom Method). The calculated results show that Young's modulus of bi-material Ni/Al does not change under the various strain rates, while the fracture strength of Ni/Al increases with increasing of the strain rates. In addition, the effects of load position and temperature on the fracture strength of Ni/Al are also investigated. With the strain rate of 1.83x108 s-1, the fracture strength of Ni/Al at 100oK and 700oK is 6.6 GPa and 4.3 GPa, respectively. The obtained results of the study are helpful in the design and fabrication of devices based on the bi-material Ni/Al.